Evolutionary history of tree squirrels (Rodentia, Sciurini) based on multilocus phylogeny reconstruction

Abstract

Pečnerová, P. & Martínková, N. (2012). Evolutionary history of tree squirrels (Rodentia, Sciurini) based on multilocus phylogeny reconstruction. -Zoologica Scripta, 41, 211-219. Tree squirrels of the tribe Sciurini represent a group with unresolved phylogenetic relationships in gene trees. We used partial sequences of mitochondrial genes for 12S rRNA, 16S rRNA, cytochrome b and d-loop, and nuclear irbp, c-myc exon 2 and 3 and rag1 genes to reconstruct phylogenetic relationships within the tribe, maximizing the number of analysed species. Bayesian inference analysis of the concatenated sequences revealed common trends that were similar to those retrieved with supertree reconstruction. We confirmed congruence between phylogeny and zoogeography. The first group that diverged from a common ancestor was genus Tamiasciurus, followed by Palaearctic Sciurus and Indomalayan Rheithrosciurus macrotis. Nearctic and Neotropical Sciurus species formed a monophyletic group that included Microsciurus and Syntheosciurus. Neotropical Sciurini were monophyletic with a putative exception of Syntheosciurus brochus that was included in a polychotomy with Nearctic Sciurus in supertree analyses. Our data indicate that Sciurini tree squirrels originated in the northern hemisphere and ancestors of contemporary taxa attained their current distribution through overland colonization from the nearest continent rather than through trans-Pacific dispersal.

Evolución de las ardillas arborícolas mesoamericanas (Rodentia: Sciuridae): un análisis filogenético molecular

“…The South American clade recovered in previous studies (Mercer & Roth, 2003;Pečnerová & Martínková, 2012) was also found in the single locus analysis. The sister taxa relationship of M. flaviventer, S. stramineus and S. aestuans was reported by Pečnerová & Martínková (2012) based on the cytochrome B, cmy exons and iRBP gene trees, all with an adequate posterior probability.…”

“…Our multilocus analysis using the most complete molecular data set recovered the general relationships previously reported in the literature Mercer & Roth, 2003;Pečnerová & Martínková, 2012), but failed to unveil novel phylogenetic relationships among Sciurus species with high posterior probabilities. This could be due to the missing data in the genes analyzed.…”

“…The sister taxa relationship of M. flaviventer, S. stramineus and S. aestuans was reported by Pečnerová & Martínková (2012) based on the cytochrome B, cmy exons and iRBP gene trees, all with an adequate posterior probability. Our current analysis also suggests this relationship.…”

“…The current data information include several genes (nuclear and mitochondrial for a total of 8) but remains poor in the number of taxa included and represented, precluding the possibilities of a more comprehensive estimation of the phylogenetic relationships. A recent combined supermatrix approach using all gene sequence publicly available (Pečnerová & Martínková, 2012) also revealed the same relationships between taxa. However, the phylogenetic relationships between Mesoamerican species remained unresolved, only supporting with low probability the sister relationship between M. alfari and S. granatensis.…”

Extreme ecological specialization in a rainforest mammal, the Bornean tufted ground squirrel, Rheithrosciurus macrotis

“…Firstly, phylogenetically it is the only species in SE Asia related to the Sciurini tribe, a large group of Holarctic and South American squirrel species. How R. macrotis colonized Borneo remains unclear because there are no known fossils that link it with the other Sciurini from which it separated some 8.6 million years ago [4][5][6]. R. macrotis also stands out because of its unusual incisors in both the upper and lower jaw, which bear a number of deeply carved ridges (~ 10) so that the incisors' cutting edge is sawshaped, an arrangement apparently not recorded among other mammals [7].…”